but i liked the goo, but i didnt like that the bottom pool of lava stopped moving once the bubbles floated up.
try making it move and squirm as it sits. i also think that a little movement up at the top would be cool too, not too much, but just enough to notice it.

the way they join and separate need a little smoothing i feel as well. its too rigid. doesnt look nearly fluid enough. good luck!